An international group of researchers has conducted a critical literature review of the use of cold thermal energy storage (CTES) in liquid-air energy storage (LAES) systems.
The role of a CTES within an LAES system is to recover cryogenic exergy during air regasification and reuse it during the liquefaction phase, significantly improving round-trip efficiency.
“This is the first comprehensive and critical synthesis of CTES for LAES,” corresponding author Alessio Tafone told pv magazine. “Rather than only reviewing existing studies, we systematically evaluate different CTES technologies, materials, and system configurations using thermodynamic and techno-economic criteria. This enables us to identify optimal design strategies, highlight consistent performance trends, and clearly map current research gaps and future development pathways.”
“While the review is centered on LAES, many of the insights are directly relevant to thermal energy storage systems for cryogenic applications more broadly, which is a key enabling technology for harnessing, storing, and reusing low-temperature thermal resources across the energy, industrial, and refrigeration sectors, liquified natural gas (LNG) regasification terminals and industrial gases sector,” Tafone went on to say.
The group’s review included the analysis of 110 publications, covering a wide range of CTES configurations, including sensible heat systems, latent heat systems using phase change materials, hybrid and cascade designs, and advanced geometries. “One of the most striking findings is how dominant cold storage performance is for overall LAES efficiency. The literature shows that cold storage losses can have up to seven times greater impact on round-trip efficiency than heat losses, which is often underestimated,” Tafone said.
The reviewers have also noted that while many high-efficiency CTES concepts show strong performance in simulations, their advantages diminish once realistic operating conditions -such as cycling, standby losses, and partial-load operation – are considered. Simpler and more robust CTES designs often perform better from a techno-economic perspective, indicating that scalability and operational reliability currently outweigh peak theoretical efficiency.
“Our analysis finds that packed beds with sensible heat materials are the most mature and cost-effective option, while phase change material-based systems offer higher efficiency potential – achieving round-trip efficiency improvements of up to 55 % – but face challenges in material cost, availability, and scalability,” the team said. “Hybrid and cascade configurations show promise in simulations, though experimental data remain limited.”
Concluding their review, the team said that although CTES research for LAES has advanced significantly in the last few years, it has remained fragmented. “To close this gap, a more coordinated and interdisciplinary research effort is needed, combining thermal engineering, material science, control systems, and economic modeling,” they added.
Tafone said that his team is now “focusing on moving beyond idealized modeling toward experimentally validated and dynamically operated CTES systems. In particular, we are interested in hybrid sensible–latent storage concepts, different geometries, long-term cycling behavior, and lifecycle techno-economic assessment under realistic operating conditions. The goal is to bridge the gap between academic concepts and deployable industrial solutions for large-scale energy storage.”
The review has appeared in “Progress and prospects of cold thermal energy storage for liquid air energy storage systems – A critical review,” published in Renewable and Sustainable Energy Reviews. The review was conducted by researchers from Singapore’s research platform Tumcreate and Nanyang Technological University, Spain’s University of Lleida, Ireland’s University College Dublin, the Technical University of Denmark, the United Kingdom’s University of Birmingham, and Poland’s Warsaw University of Technology.
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